iommu/vt-d: Prepare for killing function irq_remapping_supported()

Prepare for killing function irq_remapping_supported() by moving code
from intel_irq_remapping_supported() into intel_prepare_irq_remapping().

Combined with patch from Joerg at https://lkml.org/lkml/2014/12/15/487,
so assume an signed-off from Joerg.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/1420615903-28253-9-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
index 1e7e093..8ccc7aa 100644 (file)
--- a/drivers/iommu/intel_irq_remapping.c
+++ b/drivers/iommu/intel_irq_remapping.c
@@ -568,30 +568,6 @@ static int __init dmar_x2apic_optout(void)
 
 static int __init intel_irq_remapping_supported(void)
 {
-       struct dmar_drhd_unit *drhd;
-       struct intel_iommu *iommu;
-
-       if (disable_irq_remap)
-               return 0;
-       if (irq_remap_broken) {
-               printk(KERN_WARNING
-                       "This system BIOS has enabled interrupt remapping\n"
-                       "on a chipset that contains an erratum making that\n"
-                       "feature unstable.  To maintain system stability\n"
-                       "interrupt remapping is being disabled.  Please\n"
-                       "contact your BIOS vendor for an update\n");
-               add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
-               disable_irq_remap = 1;
-               return 0;
-       }
-
-       if (!dmar_ir_support())
-               return 0;
-
-       for_each_iommu(iommu, drhd)
-               if (!ecap_ir_support(iommu->ecap))
-                       return 0;
-
        return 1;
 }
 
@@ -616,26 +592,42 @@ static int __init intel_prepare_irq_remapping(void)
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
 
+       /* First check whether IRQ remapping should be enabled */
+       if (disable_irq_remap)
+               return -ENODEV;
+
+       if (irq_remap_broken) {
+               printk(KERN_WARNING
+                       "This system BIOS has enabled interrupt remapping\n"
+                       "on a chipset that contains an erratum making that\n"
+                       "feature unstable.  To maintain system stability\n"
+                       "interrupt remapping is being disabled.  Please\n"
+                       "contact your BIOS vendor for an update\n");
+               add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
+               disable_irq_remap = 1;
+               return -ENODEV;
+       }
+
        if (dmar_table_init() < 0)
-               return -1;
+               return -ENODEV;
+
+       if (!dmar_ir_support())
+               return -ENODEV;
 
        if (parse_ioapics_under_ir() != 1) {
                printk(KERN_INFO "Not enabling interrupt remapping\n");
                goto error;
        }
 
-       for_each_iommu(iommu, drhd) {
-               if (!ecap_ir_support(iommu->ecap))
-                       continue;
-
-               /* Do the allocations early */
-               if (intel_setup_irq_remapping(iommu))
+       for_each_iommu(iommu, drhd)
+               if (!ecap_ir_support(iommu->ecap) ||
+                   intel_setup_irq_remapping(iommu))
                        goto error;
-       }
        return 0;
+
 error:
        intel_cleanup_irq_remapping();
-       return -1;
+       return -ENODEV;
 }
 
 static int __init intel_enable_irq_remapping(void)